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The Chinese city of Shanghai is one of the fastest growing in the world. To keep up with the growth, two tunnels, three-lanes each, are being built beneath the Yangtze River to connect Shanghai with the Changxing River Island. To complete such a large project, Herrenknecht Tunneling Systems was brought in to construct the largest tunnel boring machine (TBM) in the world. The first Herrenknecht S-317 Mixshield has a diameter of 15.43 m (50.62 ft). It was built to construct one of the two 7.2-km (4.5-mile) tunnels. The tunnels are part of the Changjiang Under River Tunnel Project and will be at depths of up to 65 m (213 ft) beneath the Yangtze River in Shanghai-Pudong. These two tunnels are to be opened to traffic in April 2010, in time for Shanghai to host the World Expo. More than 20 million people live in the Shanghai area. The area itself has been growing at an extremely rapid pace for more than a decade and is in need of more space. The search extended beyond the natural limits of the Yangtze River Delta. As part of its incredible growth, 500 new vehicles are registered every day. The new tunnels will connect the Changxing River Island, with a population of approximately 600,000 people to the road traffic network. A bridge construction will also provide a traffic link between Changxing Island and the large island of Chongming.

Jan 1, 2007

By Gilman Y. Murray

The problems connected with the development of economically acceptable water supplies in arid regions are discussed. The techniques for capture and retention of runoff from infrequent desert storms are described and the major factors involved are emphasized. The exploration and planning for a typical water development in southwest United States is described, including an analysis of capital and operating costs for the proposed system.

Jan 1, 1963

By R. Jacobson

This paper presents comparison of proposed future solution and in-situ mining methods for in-situ leaching and recovery of uranium, gold, silver, and copper. We propose to show that in the future new extraction methods for each metal will eventually evolve for each hydrometallurgical process step, i.e. in-situ leaching, recovery, and concentration; precipitation and reduction; and drying, when required--without generating waste or bleed streams. In the future, to be highly profitable, these forms of mining will develop into an integrated system to eliminate waste streams using safe, powerful lixiviants. This integration will include, with some exceptions, improvements in the following areas of process development: 1. Lixiviant selection and in-situ leaching technique, 2. Target metal recovery and concentration (at a surface hydrometallurgical facility) from the circulating pregnant lixiviant stream, 3. Target metal precipitation or reduction, where decant water from the precipitate dewatering step is reusable for resin or solvent strip liquor (eluant), 4. Final preparation of target metal for sales, i.e. drying, purification, casting, packaging, 5. Restoration where most of the groundwater restoration process is performed at the same rate as multi-wellfield mining.

Jan 1, 1987

By P. D. Chamberlain

Agglomeration for the heap leaching of gold and silver ores is the process of attaching fine ore particles-less than 150 µm (100 mesh)-to coarser particles. The fines are thus immobilized and uniformly distributed throughout the heap. This is needed to make heaps more porous and uniformly permeable to the flow of a leaching solution. This article describes liquids and binders used to form agglomerates. Agglomeration techniques and equipment are also described. These include drum and disk agglomerators, stockpile and belt agglomeration, and the use of vibrating deck and reverse-running conveyors. The need for agglomeration The main reason for agglomerating heap leachable ores is to prevent percolation problems in a heap. This is different than pelletizing iron ore. In the latter case, the purpose is to bond very finely ground material into coarser, strong particles. These particles can then withstand the rigors of transportation and the loading forces in a blast furnace. Most percolation problems in heaps are caused by the segregation of coarse and fine particles during heap construction. This segregation creates areas with significantly lower permeability because fines plug the channels between coarse particles. Consequently, the leach solutions are subject to channeling, following the path of least resistance. They percolate downward through the coarse ore areas and bypass or barely wet areas that contain large amounts of fines. This results in lower extraction, longer leach time, and higher reagent consumption. Permeability problems in heap leaching are compounded because of the vertical migration of fine particles after the heap has been built. These fines eventually accumulate in pockets or layers and impede uniform solution flow. The fines move because they are not attached to a coarser particle. Moreover, the sluicing action of leach solution flowing over the surface of particles may break the bond between fine and coarse particles. Some fines are also created by the decomposition of ores after being wetted. Percolation problems are minimized if the fines can be attached to the coarser particles. Fines are thus uniformly distributed and rendered immobile within the heap. Heinen (1979) conducted comparative tests of nonagglomerated and agglomerated gold and silver ores. He showed that percolation rates through agglomerated material usually are improved by 10 to 100 times. This reduces leach time for economic recovery to less than one-third of that for nonagglomerated material, and total recovery may be increased. Cyanide consumption is also reduced in most cases because of the shortened leach time. Even run of mine (ROM) ore should be agglomerated. This can be achieved with moderate success by passing each truckload of ore under a water spray to bring total moisture of the ore up to about 8% to 10%. The ROM ore will mix when the ore is dumped, when it cascades down the slope of a heap, or when it is pushed up with a dozer. Overall, agglomeration allows low-cost heap leaching technology be applied to gold and silver ores and tailings that could not be economically processed by conventional methods, according to Phariss (1982). How agglomeration works Agglomeration means that the clays and fine particles contained in the ore adhere to the coarser particles. This creates a coating of fines around the coarse particles. When the ore has few fines and the percolation problems are not severe, the addition of a liquid may be all that is necessary to make the few fines adhere to coarser particles. However, when the quantity of fines is substantial, e.g., +10% -75 µm (-200 mesh), a binding agent may be needed. Use of solution only for agglomeration There are many forces that cause agglomeration and one of them is the surface tension of water. Water-saturated particles collide with each other or with

Jan 12, 1986

By D. W. Park

Longwall mining is popular in underground coal production in the United States due to higher production rates and safety concerns. Because of the extreme complexity, it is necessary to plan an adequate design to achieve a safe and efficient working place. The proper sizes of yield and abutment pillars and panels can be determined by simulation using numerical modeling techniques. By means of three-dimensional modeling, stresses to be imposed on the pillars, panels, gob, and powered supports can be analyzed. In this study, an initial three-dimensional finite element model was developed and then modified into four different models. Using these models, the numerical outputs of distributed stresses on three different sizes of yield pillars, three different sizes of panels, and two different sizes of abutment pillars were compared and analyzed to determine the most adequate pillar and panel sizes. Progressive failure theory based on the Hoek and Brown failure criterion was used to determine redistribution of stresses in the yielded and failed areas in the longwall mine.

Jan 1, 1992

"INTRODUCTION The characterization of groundwater hydrogeology is a common component in feasibility studies, geotechnical investigations and regulatory permitting for mining operations. The lithology at a location of interest may include several discrete water-bearing units; and the means of isolating each for testing can be accomplished through the use of inflatable packers. Consideration for testing during drilling program planning and communication between all stakeholders is essential to ensure that the Mine, Drilling Contractor and Hydrogeological Testing Specialist (Specialist) are ready to perform packer testing when the call is made to mobilize. Often, the notice to mobilize can be delayed and then occur with little warning due to the issues that can occur during drilling of very deep boreholes, as well as other factors. Hydrogeological investigation reports and journal articles generally discuss testing methods and results, with limited information available describing the planning and coordination of the field testing program, as evidenced by the lack of references cited below. The source of inspiration for the subject matter of this paper is grounded in the author’s past shortsightedness; with the hope that others not share similar misfortunes but experience success through thorough preparation for their future hydrogeological testing programs. The sections below focus on the planning stages of a field investigation using inflatable packers, including considerations for site specific conditions, designation of stakeholder responsibilities, and communication of testing expectations. Following these sections is a presentation of two examples of successful field programs and lessons learned in addressing problems encountered along the way. PRELIMINARY PROGRAM PLANNING & CONSIDERATIONS From the onset of planning for drilling programs, the Specialist should be in communication with the Mine to review plans and identify fatal flaws which could impede collection of hydrogeological data. Preliminary scope decisions can significantly affect the budget and duration of hydrogeological field programs and may dictate the means by which the field data is collected. The issues that need to be considered include the following factors. Testing Objectives The setup of the packer tool is dependent on the testing objectives. Is the goal to estimate bulk aquifer hydraulic conductivity or to identify discrete discontinuity hydraulic characteristics? Are groundwater samples needed? The answers to these questions affect selection of test interval length and what instrumentation might need to piggyback on the packer tool. Identifying the testing goals initially will provide adequate time to prepare packer equipment for mobilization. Borehole Size While inflatable packers come in many shapes and sizes, some sizes are more readily available and easier to procure on short notice. Packers for NQ and HQ size boreholes have been historically easy to procure and are commonly used in exploration drilling. Packer equipment is available for smaller holes, but it becomes more difficult to fit instrumentation down-hole as the borehole size decreases. This is particularly a consideration if collection of groundwater samples is required. In addition, risks of losing the hole or equipment downhole are greater for smaller boreholes. Larger boreholes require larger packers and clearly require more effort and heavier capacity machinery to manually manipulate due to the increased size."

Jan 1, 2017

By T. J. McKeon

Gravity separators such as spirals are commonly used in multistage cleaning and scavenging circuits to improve the quality and recovery of concentrates produced in the industrial minerals industry. Unfortunately, field surveys suggest that many industrial operations are poorly configured in terms of equipment layout. This shortcoming can often be attributed to a failure by engineers to make use of fundamental process engineering tools for circuit design. One of the most important of these is linear circuit analysis. This powerful tool makes it possible to mathematically compare the relative efficiency of circuit configurations in advance of experimental testing. This article provides a basic review of the linear circuit analysis concept and discusses some of the key insights it provides for the layout of multistage circuits. An industrial case study is provided to show the tremendous impact that this process engineering tool can have on the design of multistage spiral circuits in a heavy mineral wet plant.

Feb 1, 2012

By J. P. A. Hortley

In conventional electrolytic copper production, looped copper starter sheets, on which the copper is deposited, are supported by hard-drawn copper bars. These bars have cross-sectional areas of between 1 and 1.4 in2. The suspension bars serve two purposes: firstly to support the cathode, which can weigh up to 150 kg, and secondly to introduce the electric current. IYI examined these two requirements in detail to see whether a better design could be achieved. Considering firstly the current carrying requirement, it wee noted that under normal refinery conditions, each cathode carries between 400 and soak. If one applies the generally accepted rule that 1 in of copper can carry 1000A4 a suspension bar need theoretically contain only 1/2 in2 of copper. This contention is supported by the fact that the 500A current passed through the cathode also appears to pass quite satisfactorily through the two support loops, which have a cross-sectional area of approximately 0.35 in 2. Turning now to the strength requirements, the cross-section of hard-drawn copper bar required to support a 150 kg cathode is relatively small, and easily met by the present designs. It is not, however, the static load applied by the 150 kg cathode immersed in the electrolyte which causes the damage to the hard-drawn copper, or even the increased static load of a 100 kg man standing on one foot in the centre of the bar; the damage is actually caused by the dynamic loads applied to the bare when they are dropped, thrown into containers, lowered too rapidly into the cell, or otherwise mistreated. The important requirement is therefore that the bar does not permanently bend. Its proof stress of limit of proportionality, rather than the amount that it deflects under static loading, should be the strength criterion. With the hard-drawn copper normally used for the manufacture of suspension bars, it has been observed that the copper becomes annealed during use, particularly at the end of the bar where the current is introduced. Thus, after a relatively short time, the cathodes are in effect being supported by annealed copper bars.

Jan 1, 1978

By M. F. Corcoran

Rapid advances have been made in the past few years in the application of automatic controls and instrumentation to iron ore pelletizing plants. Present practice in applying instrumentation and control to the Grate-Kiln system of iron ore pelletizing is described. Major control points and loops are tabulated. Future trends in the application of digital control including computer data logging systems are described.

Jan 1, 1965

By Kevin Lundberg, Philip Sander, Daniel Weinberger, John Reilly

Since the early days of risk management, developments in technology and guidelines (ITA, ITIG, OGG, UCA) have advanced risk management and probable cost estimating, which are now widely recognized. WSDOT’s CEVP risk-based cost validation process is now established after 20 years. This paper traces these developments, summarizes advanced techniques, and presents examples of US and international projects with results. A particular case of using advanced risk evaluation to allow enhanced-capability TBMs to be considered in a competitive bid process is presented. Further advances, including the use of digital twin risk-based representation of complex projects, are described.

Jun 13, 2023

By E. J. Sullivan

This study seeks to define the mechanism of oxyanion sorption onto surfactant-modified zeolites. Zeolites which have been treated with hexadecyltrimethylammonium bromide (HDTMA) surfactant to produce a hydrophobic surface are capable of sorbing both organic compounds as well as oxyanions such as chromate, selenate, and sulfate. Simple ion exchange and charge-balancing mechanisms do not fully explain this unusual phenomenon. The sorption of HDTMA surfactant appears to be partly ion exchange and partly sorption to non-ion-exchangeable sites. Sorption of chromate is a simple exchange mechanism with bromide, which co-adsorbs with HDTMA to form a surface precipitate. Information from this study will be used to design on-site and in situ treatment systems for contaminated water, such as filter beds and permeable barriers.

Jan 1, 1995

By Jane Morrison

Permanent magnets are used in most electromechanical and electronic devices to convert electrical to mechanical energy and vice versa. More than fifty are commonly found in the average American home and car. A new species of permanent magnet composed of iron, neodymium, and boron has recently been developed which combines superior magnetic properties with compact size. The reduced size of the magnets has enabled significant new developments in such areas as robotics and consumer electronic, among others. The objective of the present work is to efficiently and economically separate valuable rare earth materials from the relatively worthless iron constituent in NdFeB magnet scrap. Several magnet producers have expressed interest in the development of such a process and have provided information and scrap samples to aid in research. Scrap is generated in a variety of forms from different stages in the processing stream. Pieces of magnetic and non-magnetic metal as well as sludge and ribbon from jet casting must all be treated. Beneficiation techniques have been studied and size distributions developed for the different scrap types. Slag from the casting process is resistant to crushing and may need to be embrittled first, but all other types are amenable to crushing and ball mill grinding using stainless steel balls and water. Tabling was found to be useful in classification of magnet sludge. Two major techniques for separation of rare earths have been studied:

Jan 1, 1990

By William F. Tanner

A river delivers a given load of sand, and hence of heavy minerals, into the sea into which it empties. This load is fixed by drainage basin characteristics and processes. Wave energy available for redistributing that load is fixed in an entirely different way. An equilibrium diagram of these two parameters (load versus energy) permits a tentative prediction of what will happen to the heavy minerals. The Chattahoochee River delivers a load which, over the past few thousand years, appears to have been greater than the available coastal energy could handle. As a result, much of the sand has been accumulated in various delta-margin features: barrier islands, beach ridges, and large furrowed off-shore shoals. The bulk of the trapped sand is found today in the shoals, which are attractive deposits for possible exploitation. If coastal energy levels are high enough to move the total load delivered by the river, accumulations of sand (and hence of heavy minerals) should be sought in the down-drift direction. Energy levels are rarely constant over any great length of coast. Decreases in energy may be due to widening of the shelf, convexity of, the shore, restrictions on the fetch, wave decay, or other causes. Such decreases result In deposition. Hydrodynamic mapping of coastal areas, as outlined here, should prove useful in the location of additional reserves. Part of this type of work can be done on maps, charts, and air photos.

Jan 1, 1962

By Silas Li, Michael Harris-Gifford, Jason Choi, William H. Hansmire

Twin-bore tunnels with a single track in each tunnel are currently the most common subway tunnel configuration. However, a large diameter single-bore tunnel with two tracks separated by a center wall could replace twin-bore tunnels and introduce potential benefits but require necessary modifications to the subway system. In particular, a nominal 40-foot-diameter single-bore tunnel can be considered in lieu of nominal 20-foot-diameter twin-bore tunnels. This paper discusses the benefits and modifications introduced by replacing twin-bore tunnels with a single-bore tunnel, with respect to various elements of the subway related to the tunnel, stations, track, and tunnel systems.

Dec 1, 2022

By Tyler A. Dawson, Ryan P. Butler, Timothy Gualandri, Jason R. Edberg

"In the early 1920’s, the City of Tulsa, Oklahoma constructed an approximately 8,238-foot long tunnel, the Tiawah Tunnel, through bedrock. Voids behind the concrete tunnel liner were detected via probe drilling in early 2000 as part of an interior visual condition assessment. In 2012 and 2015, conditions along the entire tunnel were efficiently assessed through geophysical investigation using ground penetrating radar (GPR) along the inner tunnel crown and at various select locations within the tunnel. Fifty-seven (57) potential voids, extending up to 19 inches in depth and 12 feet in width, were detected with 1,000 MHz GPR and confirmed through probe drilling with approximately 80% accuracy. GPR proved to be an efficient and reliable technology for void detection behind concrete tunnel lining. This paper highlights the geophysical investigation and how geophysical efforts were combined with other investigation efforts to definitively determine the presence of voids outside of the tunnel lining.INTRODUCTION The city of Tulsa, Oklahoma has a population of about 400,000 people. The original source of water for the city was the Arkansas River. The first pumping operation provided untreated water to homes and businesses in 1904. The residents of Tulsa found this water to be unacceptable due to the high levels of salt and gypsum present. As the city grew, land and storage/treatment facilities were acquired in order to obtain and distribute a more suitable raw water. The raw water needs for the city are currently satisfied by transport and treatment of about 100 million gallons per day (MGD) of water from surface water sources. Water is transported many miles from Spavinaw/Eucha and Oologah lakes to Yahola Lake and the Lynn Lane Reservoir (totaling over 3-billion gallon capacity). From here, the raw water is treated and transported to the various customers (City of Tulsa 2015). The Tulsa Metropolitan Utility Authority (TMUA) is responsible for the operation and maintenance of the raw water transport system."

Jan 1, 2016

By Javad Sattarvand, Frimpong Kwaku Asare

The safe evacuation of miners during an emergency in the shortest amount of time is one of the most essential features of a mining operation. Despite advancements in mine evacuation research, the usage of mine vehicles during evacuation has not been considered. The majority of recent studies have been done on miners’ evacuation on foot. Mathematical formulations including Minimum Cost Network Flow (MCNF) models, Dijkstra's algorithm, Floyd-Warshall algorithm, and Ant Colony Optimization models have been used to solve mine evacuation problems. These models, which concentrate on determining the shortest escape routes during the evacuation, have been found to be computationally expensive and may not offer the best solutions in some cases. The goal of this paper is to incorporate light vehicles in the evacuation process using a mixed-integer programming approach. The methodology aims to minimize the total time required to evacuate the mine, ensuring minimal exposure of the miners to the adverse conditions that triggered the evacuation.

Jun 25, 2023

By Jugal Kar

Yilgam Star treats a gold bearing ore which has an association with pyrohotite and pentlandite (Fe,Ni)9S8 Nickel behaves similar to gold in cyanide solution, it leaches in cyanide to form a number of species. It adsorbs like the noble metals on carbon. During smelting Nickel causes significant problems in the crucible as the melting point of nickel is much higher (1452 °C) than gold (1040 CC). The crucible became overheated, holed and increases furnace downtime. To overcome such dif­ficulties an investigation was carried out to reduce the amount of nickel on steel wool during stripping. Yilgam Star has got I.P.S. high pressure zadra stripping system which works on 400 kpa, at 140 °C. The trend of gold and nickel profiles has been observed with varying caustic concentrations. The gold and nickel profile has been monitored with the addition of cyanide in the stripping liquor. It has been ascertained that at lower caustic levels the nickel ion remains in solution and is subsequently not electro­won. The cyanide concentration of0.4% (Wt/Vol) keeps nickel ion in solution and induces metallic nickel to produce nickel ion as NiCN.

Jan 1, 1995

By G. M. Bernard

Cerro Colorado lies on the eastern edge of the Atacama Desert in the foothills of the Andean Cordillera of northern Chile. Compañía Minera Cerro Colorado SA (CMCC) operates Cerro Colorado. CMCC, headquartered in Santiago, Chile, is wholly owned by Rio Algom Ltd., of Toronto, Ontario. Cerro Colorado is located 120 km (75 miles)east of the port city of Iquique. Access is by 30 km (19 miles) of paved highway and 70 km (43 miles) of upgraded road. The mine site is located at an altitude of 2600 m (8531 ft) on a gentle west-sloping plateau adjacent to a deep canyon (Quebrada de Parca) to the north. Temperatures are moderate, ranging from 5° to 30° C (41° to 86° F) with an average annual rainfall of 20 mm (0.8 in.). The plateau is generally covered with 20 to 30 m (65 to 100 ft) of Quatemary sand and gravel overlaying bedrock. In the immediate vicinity of the Cerro Colorado deposit, a semicircular embayment has been eroded into a steep canyon wall that cuts through the surface gravels to expose a considerable section of the underlying bedrock.

Jan 1, 1995

By G. M. L. Robinson

Mineral Processing Wastes, as defined by the Environmental Protection Agency (EPA), has determined that most of the mine wastes will be regulated pursuant to subtitle D (Solid Waste Regulations) of the Solid Waste Disposal Act while specific mine waste categories will be regulated within the framework of the Toxic Substance Control Act. Though EPA's determination currently relieves the industry of the regulatory constraints mandated by the Resource Conservation and Recovery Act (Hazardous Waste Regulations) Subtitle C regulatory framework; the industry is not granted immunity from historical or current environmental regulations related to listed or characteristically hazardous or solid wastes. Because of the current regulatory trends and the need to implement cost effective remediation alternatives; advanced currently available on-site remediation technologies are available to minimize, reduce, contain or prevent environmental impacts related to mining and processing activities. In light of industry technical needs, an overview of the research and commercially available remediation technologies will be discussed and a brief discussion of the strengths and weakness of each technology will be presented. Technologies to be discussed includes stabilization, solidification, soil wash, soil flush, thermal distillation, pump and treat, metal extraction, centrifuges, filter presses, bioremediation, and incineration.

Jan 1, 1992

By G. A. Hufford

The cutoff grade applied to a disseminated orebody mined by open pit affects both the waste ratio, hence the cost of producing ore, and the ore grade, hence the quantity of metal recovered. As such it has a significant impact not only on the annual profit or loss, but also on the life of a mining property. Cutoff Grade Strategies Some commonly used objectives in calculating cutoff grades are as follows: Minimize Unit Cost of Product (1) This is found by adding all costs associated with each possible cutoff such as mining, processing, and marketing. This is divided by the quantity of marketable product obtained at each cutoff grade, then finding the minimum. Because the market value of the product does not enter the calculation it has no effect on this strategy: the same cutoff is selected in good times and bad.

Jan 1, 1986